On Mon, Jan 09, 2023 at 03:37:53PM -0700, Nathan Chancellor wrote: > On Mon, Jan 09, 2023 at 04:23:37PM -0600, Segher Boessenkool wrote: > > Hi! Happy new year all. > > > > On Mon, Jan 09, 2023 at 01:58:32PM -0800, Nick Desaulniers wrote: > > > On Wed, Jan 4, 2023 at 11:55 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > > > > > > > When clang's -Qunused-arguments is dropped from KBUILD_CPPFLAGS, it > > > > warns that ASFLAGS contains '-s', which is a linking phase option, so it > > > > is unused. > > > > > > > > clang-16: error: argument unused during compilation: '-s' [-Werror,-Wunused-command-line-argument] > > > > > > > > Looking at the GAS sources, '-s' is only useful when targeting Solaris > > > > and it is ignored for the powerpc target so just drop the flag > > > > altogether, as it is not needed. > > > > > > Do you have any more info where you found this? I don't see -s > > > documented as an assembler flag. > > > https://sourceware.org/binutils/docs/as/PowerPC_002dOpts.html > > > https://sourceware.org/binutils/docs/as/Invoking.html > > > > It is required by POSIX (for the c99 command, anyway). It *also* is > > required to be supported when producing object files (so when no linking > > is done). > > > > It is a GCC flag, and documented just fine: > > https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html#index-s > > > > (Yes, that says it is for linking; but the option is allowed without > > error of any kind always). > > > > (ASFLAGS sounds like it is for assembler commands, but it really is > > for compiler commands that just happen to get .S input files). > > > > > The patch seems fine to me, but what was this ever supposed to be? > > > FWICT it predates git history (looking at > > > arch/powerpc/kernel/vdso32/Makefile at fc15351d9d63) > > > > Yeah, good question. This compiler flag does the moral equivalent of > > strip -s (aka --strip-all). Maybe this was needed at some point, or > > the symbol or debug info was just annoying (during bringup or similar)? > > > > > Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > Reviewed-by: Segher Boessenkool <segher@xxxxxxxxxxxxxxxxxxx> > > Thank you for the review and extra explanation! I had kind of expanded > on this in the s390 version of this patch [1], I will go ahead and do > the same thing for the powerpc version too. > > [1]: https://lore.kernel.org/llvm/20221228-drop-qunused-arguments-v1-9-658cbc8fc592@xxxxxxxxxx/ The underwhelming GCC source code for this is https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/gcc.cc;h=d629ca5e424ad3120be13e82b9f38b7bf8f1cdf2;hb=HEAD#l1148 which says that the -s flag is passed through unmodified to the linker when invoking the linker. See #l603 for the %{s} specs syntax. This is not a flag to the assembler at all. It is a flag to the compiler, which passes it on to the linker :-) > > (ASFLAGS sounds like it is for assembler commands, but it really is > > for compiler commands that just happen to get .S input files). Segher
